202 THE LARYNX, BRONCHI AND OESOPHAGUS The principle of treatment is to remove the papillomata as they appear, without damaging the larynx in the process, and to wait for the normal resolution of the condition. It is also important to do everything possible to prevent spread down the tracheobronchial tree and to this end avoidance of a tracheostomy is of vital importance when one considers how the tumour is implantable. If the tumour affects the tracheobronchial tree the patient is in danger of death because of stenosis and scarring of that vital region. Many treatments have been advocated over the yearsadministration of oestrogens, cautery with podophyllin, trichloracetic acid or chromic acid, ultrasonic therapy, irradiation, vaccine therapy and local idoxuridine. None of these is as successful as careful and repeated local removal, aided by the microscope, and regular 2-monthly follow-up of the patient until the condition resolves some time in the late teens. This policy is safer than waiting until respiration becomes embarrassed because by then so many landmarks have disappeared that laryngeal damage and subsequent scarring are inevitable. STENOSIS Laryngeal atresia represents the ultimate in stenosis and is inconsistent with life unless it is recognized at birth and a tracheostomy performed. It is, in fact, a web filling the whole larynx and it is commonest in the subglottic region. Congenital laryngeal web consists of a membrane lying between the vocal cords always at the anterior part of the glottis (Plate VHI94). The membrane is quite tough and the degree of stridor and aphonia is proportional to the size of the web. A small web will cause little respiratory difficulty and may safely be left until the larynx has stopped growing since it only causes slight dysphonia and not dyspnoea. A large web, however, should be dealt with immediately because the only alternative will be a permanent tracheostomy. The thyroid cartilage is divided in the midline and the web is excised. If the larynx were to be closed at this point, the raw anterior ends of the vocal cords would adhere causing further glottic stenosis, and so it is necessary to close the larynx over a McNaught keel (Fig. 98, p. 195). This is made of 0-18-mm thick tantalum sheeting and it is left in place for at least 5 weeks. During this time the patient breathes with a temporary tracheostomy. After 5 weeks the keel is removed. Medium size webs may be removed at microlaryngoscopy, the anterior ends of the vocal cords being injected with steroid to try to prevent adhesions forming. Subglottic stenosis may be caused by a congenital narrowing of the cricoid cartilage. It is said to be established if the internal diameter of the cricoid ring is less than 3-5 mm. It can also be caused by an improperly performed high tracheostomy. STRUCTURAL ANOMALIES Cleft larynx is really a high tracheo-oesophageal fistula. In its complete form, where the cleft goes through the whole lamina of the cricoid cartilage and the posterior wall of the trachea, death from aspiration of food and saliva is inevitable. If the deft does not go completely through the cricoid lamina, however, it can be repaired in layers and the cleft closed.